December 2008

Welcome to the latest newsletter and we hope that you will enjoy reading it.

Cliff Turk, from the Cape Town ASSA, gave an informative presentation on light pollution. He explained that the current international awareness campaign had started with astronomers experiences growing problems with growing cities becoming strongly lit at night by uncontrolled and inefficient light.

Excessive artificial light at night was also having a serious effect on the environment as a whole: sleep deprivation, especially in young children, disruption of birds’ breeding patterns, adverse effects on insect populations, and, in some areas, even extinction of some species in both the animal and the flora environments. Safety and security, the main justification given for bright lighting at night were, in fact, being incorrectly addressed and responsible for poor use of precious energy. The development of new designs and standards was being sucessfully applied in many cities today, resulting in better lighting on the ground where it is wanted and considerable power cost savings being shown in all cases. Several cities and authorities have adopted new legislation at community levels and, in one European country, nationally.

The talk was very well received. The Municipal Manager indicated that he will push for new standards and, possibly, by-laws to control “nuisance” lighting. Also, he local supply trade will search for suppliers of fittings which conform to the latest “full cut-off” requirements.

Progress is being made on securing a suitable site for the new observatory. Meetings and discussions have helped to narrow down the range of possibilities, and the work of the committee is moving towards identifying the likely site.

Plannoing for the 2009 programme continues. If any member wishes to give a presentation or knows someone who may be interested in doing so, please contact a committee member.

A further reminder that club meetings for 2009 will be changed to coincide with the phases of the ‘New Moon’ in order to allow better star-gazing visibility. From January through June it will be the fourth Thursday in the month and from July to December it will be the third Thursday evening. Once these dates have been secured with the Botanical Society for the use of the Fernkloof Hall, you will be advised.

1. As astronomers explore newly discovered planets and create computer simulations of virtual worlds, they are discovering that water, and life, might exist on all manner of weird worlds where conditions are very different from those on Earth. This means there could be many more habitable planets out there than we thought possible. “It’s like science fiction, only better,” says Raymond Pierrehumbert, a climate scientist at the University of Chicago, who studies planets inside and outside of our solar system.

2. NASA is experiencing problems with a $250 million machine for recycling urine and other wastewater into drinking water for astronauts. NASA delivered the water regeneration system to the $100 billion International Space Station this week to prepare for its crew to grow from three members to six in May.2009. Glitches triggered two shutdowns during initial attempts to begin the distillation process on pre-collected samples of urine.

Residents of the station must recycle water because the space shuttles, which produce water as a byproduct of their electrical systems, will no longer fly to the outpost after 2010 and it is too expensive to haul as much water as the crew will need on unmanned cargo ships from Earth.

3. A planet may have been imaged closer to its star than any photographed previously, astronomers say. The candidate planet, which might still turn out to be a foreground or background object, appears to lie at about the orbital distance of Saturn around the well-studied star Beta Pictoris.

Astronomers have long suspected that the young, 12-million-year-old star hosts a massive planet, since it is surrounded by a dusty disc of debris thought to be created by the collision of rocky bodies and infalling comets.

4. Ice glaciers hundreds of metres deep are lurking just underneath the Martian surface around the planet’s mid-latitudes, new radar measurements suggest. The discovery represents the largest cache of ice yet found beyond Mars’s polar regions and bolsters the case that the planet’s tilt changes periodically. The ice could also be an ideal place to study the ancient Martian climate and look for evidence of life.

The glaciers, found at latitudes between 30 and 60° in both the northern and southern hemispheres, sit underneath fields of rocky debris. The appearance of the landscape suggests the debris flowed from hills lying up to 20 kilometres away.

5. An apparently isolated galaxy whose frenetic rate of star birth had puzzled astronomers actually lies 1.5 times as far away as previously thought, a new study reveals. The new distance measurement suggests the galaxy may be falling into a crowd of about 10 other galaxies, whose gravitational tugs could explain its stellar baby boom.

Ground-based telescopes had previously gauged the distance to the dwarf galaxy, called NGC 1569, to be about 7 million light years from Earth. At that distance, the galaxy appeared to lie in a region of space devoid of other galaxies. Most such galactic loners tend to evolve slowly, eking out stars at a relatively modest rate because they lack neighbours whose gravitational tugs can trigger the galaxies’ own gas clouds to collapse into stars.

But NGC 1569 is churning out new stars at a breakneck pace. “It is forming stars at a very high rate – much higher than any other galaxy in the nearby universe,” says lead author Alessandra Aloisi of the Space Telescope Science Institute in Baltimore, Maryland. “That is only seen in galaxies that are interacting or merging with each other.” Now, a new study based on Hubble Space Telescope observations shows that the galaxy does indeed have neighbours.

This month, our overview of plants of the solar system focuses on Jupiter, the giant gas planet, and its moons.
Jupiter & its Moons

In Roman mythology Jupiter was King of the Gods, and God of rain, thunder, and lightning, which is an apt name for by far the largest planet in the Solar System.

318 times more massive than Earth, it has almost 2.5 times the mass of all the other planets in the solar system put together. It is comprised mostly of the gases helium and hydrogen with a very small core of rock and metal.

Jupiter has an elliptical orbit round the Sun and its year is 11.86 Earth years in duration. One of the most surprising features is its extremely fast rotation of just under 10 hours.

Jupiter is renowned for its Giant Red Spot which is a huge anticyclonic cloud formation that swirls in an anticlockwise direction and is more than twice the diameter of Earth in size. It also has a very thin Saturn-like ring system which was only revealed in 1979 by the Voyager 1 spacecraft.

Apart from the four major planets (the Galileans) named in our August ‘Southern Cross’ Newsletter – Io, Europa, Ganneymede and Callisto, there are over sixty other known moons. Many are named after characters in Greek and Roman mythology, including:

• Metis (diameter of only 40km’s and the closest moon to the planet);
• Adrastea (26km in diameter);
• Thebe with one particularly large crater on its strangely shaped surface (110km diameter);
• Amalthea, a very strange shaped moon, discovered in 1892 (262km diameter);,
• Themisto, believed to be the most recently discovered moon and orbiting the planet at a distance of 7.5 km’s. It was first discovered in 1975 and then lost and only rediscovered in November 2000. With a diameter of only 8km it is perhaps not surprising that it was lost for so many years.

Like the ring system, many of the moons were seen for the first time by the Voyager 1 space programme in 1979.

11th Dec – Christmas Party


John Saunders (Chairman) 028 314 0543
Steve Kleyn (Technical Advisor) 028 312 2802
Pierre de Villiers (Treasurer) 028 313 0109
Irene Saunders (Secretary) 028 314 0543
Piet Daneel 028 314 0947
Pierre Hugo 028 312 1639
Jenny Morris 071 350 5560

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